/Engine/Source/Runtime/Engine/Classes/GameFramework/GameSession.h
Get the current joinability settings for a given session
true if session exists and data is valid, false otherwise
virtual bool GetSessionJoinability ( [FName](API\Runtime\Core\UObject\FName) InSessionName, [FJoinabilitySettings](API\Runtime\CoreOnline\Online\FJoinabilitySettings) & OutSettings )